Dogal Afetler ve Cevre Dergisi

216 - 239

Authors: Vedat AVCİ ; Ömer ÜNSAL

This study aims to analyze the flood disaster that occurred in Kastamonu-Bozkurt in 2021 through the morphometric parameters of the basin. In the study, the Basin of Ezine Stream, which is the flood experienced most effectively, was analyzed together with the neighboring basins. Bozkurt flood is one of the most destructive floods in the history of Türkiye. As a result of the floods that occurred in Kastamonu and neighboring provinces on 10th - 12th August 2021, 82 people lost their lives. The Digital Elevation Model (DEM) of the study area was created with a cell size of 10*10 m using topography maps, and the boundaries of the basins to be analyzed with the ArcGIS-Archydro Module were determined. 30 indices were applied to these basins within the scope of shape (geometric), areal and relief morphometric features of the basins. The relationship between morphometric parameters was determined with the Pearson correlation coefficient. When the analysis results are evaluated for the Basin of Ezine Stream, it is the basin with the largest area, and the largest value of basin relief, relative relief and ruggedness. As a result, erosional activities and the risk of flood are high. When all basins are evaluated in general, it has been revealed that the shape of basins are more elongated, and the features of relief morphometry facilitate the formation of floods. Basin relief, relative relief, dissection degree, slope values, and average slope values are high for all basins; and both the amount of water added to the overland flow and the speed of the overland flow increased. This situation also increased the amount of material carried during the flood. Constructions built close to the stream bed increased the effect of the flood. Depending on the global climate change, the study area corresponds to the area where the change in daily maximum precipitation varies between 5-10%. Therefore, floods are likely to continue. For this reason, it is recommended to consider geometric, areal and relief morphometric features of the basins along with the climatic features of the basins while taking the necessary precautions. According to CORINE land cover data, urban areas in the Ezine Stream Basin increased by over 100% between 1990 and 2018, which is also affected by disastrous floods and overflows. Conservation and strengthening of natural vegetation in the study area will reduce the damage level of floods and overflows.

258 - 267

Authors: Can BAŞARAN; Hüseyin MANAP

The water points located in the northwest part of the Afyon Plain are used as mains and irrigation water, by approximately 8000 people approximately 56 km2 of agricultural land. In order to use water resources effectively and efficiently, it is necessary to know the physical, chemical properties and the qualities of the waters very well. For this purpose, 12 groundwater were sampled within the scope of the study, and the hydrgeoochemical processes that gave the current compositions of the waters were determined, the analysis results were compared with the standards, and the irrigation water quality was Electrical conductivity (EC), Schoeller and Wilcox Diagram, Sodium Hazard (%Na and SAR), Residual Sodium Carbonate. (RSC), Magnesium Ratio (MR), Potential Salinity (PS) and Kelley index (KI) were interpreted using parameters. According to the analysis results, it was determined that the major cations of the waters were Ca, Mg and Na, and the major anion was HCO3. The schists and carbonate rocks cropping out in the region affect the current composition of the waters. However, the elements such as nitrate, arsenic, fluorine and boron, detected at some water points and exceeding the limit value may originate from domestic-agricultural wastes and fertilizers. The sampled waters should be used carefully and necessary precautions should be taken in terms of drinkability and irrigation water characteristics.

279 - 294

Authors: Pınar POLAT; İbrahim KOPAR; Fatih YALÇIN

The research area is Günebakan, which represents a large number of parallel drained river basins located in the south-southwest part of the Keşiş (Esence) Mountains (Keşiş Tepe, 3549 m) that border the Erzincan Plain from the north in the northwest (NW)-southeast (SE) direction. The stream includes the Allahmedet Stream and Çadırtepe Stream basins. In this study, the formation and development processes of two flood-overflow events that occurred in Günebakan Stream Basin, the first on 17/07/2011 and the second on 03/07/2020, in the size of a natural disaster and resulted in significant property losses, and their effects on the natural and human environment were examined. In addition, the morphometric characteristics of the Günebakan, Çadırtepe, and Allahmedet stream basins, which are adjacent to each other in the south-southwest catchment area of the Esence Mountains, which surround the Erzincan Plain from the north, were revealed and their flood-overflow potentials were investigated. In this context, with an approach that prioritizes the flood-overflow events occurring in the Günebakan Stream basin, areal, linear, and relief morphometric indices were used to determine the effect levels of the basin morphometry in the flood-overflow events that occur or are likely to occur on the existing running waters. In the analyzes carried out, it was observed that there was a close relationship between the morphometric structure of the relevant basins and the debris-laden floods. In addition, it was concluded that the Günebakan Stream basin in the same catchment area has a higher flood and overflow potential compared to the neighboring basins.

311 - 323

Authors: Mustafa UTLU; Mehmet Fatih AKGÜMÜŞ

This study focuses on the high-resolution 3D cone-based rockfall modeling using Qproto, a QGIS plugin, based on UAV-DSM data in an area near Mazı Village, located north of Derinkuyu and Ürgüp districts in Nevşehir province, where rockfall events occur intensively. The volcanic ignimbrites corresponding to the source zones in the study area have steep and vertical slope profiles, particularly resembling cornices. Therefore, 16 rock blocks with a potential for rockfall were identified within the rock mass structure characterized by cooling cracks (vertical discontinuities) commonly observed in ignimbrites where discontinuities near the vertical occur. Rockfall modeling was performed for these identified blocks. According to the modeling results, rockfalls with a maximum kinetic energy of 142 kJ and a displacement velocity of 16.8 m/s were determined. Based on these results, the maximum values of the rockfall model within the study area were generally reached in areas with high slope values, and it was observed that the energies and velocities of rock blocks attenuated at points with decreased slope, indicating the influence of the existing gravitational condition. Rockfall susceptibility degrees were categorized into five classes, and it was observed that the trajectories of fallen blocks, resulting from rockfalls, corresponded mainly to the moderate-high and high susceptibility classes, where they were scattered and dispersed.

341 - 364

Authors: Mustafa Utku YILMAZ

This study aimed to provide a comprehensive drought analysis for Kırklareli province, whose economy is largely based on agriculture. The trend and temporal variability of drought were examined at 1, 3, 6, 9, and 12-month time scales using the Standardized Precipitation Index (SPI) and Reconnaissance Drought Index (RDI). The monthly precipitation and temperature data from the Kırklareli meteorological station between water years 1960-2021 were used to calculate the SPI and RDI. Mann-Kendall and modified Mann-Kendall tests were used to determine trends of SPI and RDI series for different time scales, Sen’s slope was used to identify the magnitude of trends in the series, and Pettitt's test was used to detect the change point of the series. The results revealed that the SPI and RDI behaved similarly for all time scales and both indices were able to capture almost the same drought events. Besides, it was observed that SPI had a strong linear relationship with RDI over the same time scale (r=0.99). RDI mostly had slightly higher values than SPI and it was concluded that RDI was more sensitive in the detection of extreme and severe drought events. The percentages of occurrence of drought events at different time scales ranged from 46.9% to 51.3% for SPIs and between 47.2% and 50.6% for RDIs. In the 12-month time scale for both indices, 76 months between February 1989 and May 1995 were determined as both the longest and the most severe dry period. As the time scale increased, the number of drought events decreased and the drought duration increased. No statistically significant trend was found for SPI and RDI values at all-time scales (p>0.05). For both indices, there was no change point in the 1-month time scale, but the change point was identified in the 3, 6, 9, and 12-month time scales.

385 - 403

Authors: Ece POLAT; Hülya ÜNVER; Mahmut ALTINBAŞ

Mucilage formation is a very complex phenomenon involving various biological and hydrological interactions. Mucilage is formed as a result of bacterial and phytoplankton-based activities in the environment. Oceanic shifts can provide an environment favorable for mucilage development; however, other factors also play a role in forming mucilage. Mucilage's microbiological structure and morphology, which have been studied in many waters and habitats since the 17th century, are also distinct. This is due to the fact that mucilage development is largely taxon-specific, and mucilage thickness and texture vary depending on environmental conditions. In mucilage studies, phytoplankton is the main component. A high level of organic matter and nutrients in the environment stimulates the formation of phytoplankton and the microenvironment. Furthermore, various water properties, such as temperature, fluidity, and so on, have an increasing effect on mucilage production. The purpose of this review is to describe how aggregates and mucilage are produced by dissolved organic matter (DOM) and microbial populations. Then, living groups discovered in the structure of mucilage during microbial ecology researches are discussed. Several examples of living organisms negatively affected by the development of mucilage were discussed following a detailed description of the dominant species observed in mucilage regions and case information.